The COVID19 vaccination is currently only available through the UK Government Vaccination program. Information on the vaccine, who can get vaccinated and how to arrange this, is available at https://www.nhs.uk/conditions/coronavirus-covid-19/coronavirus-vaccination/ or by telephone, dial 119
It is important that you are registered with an NHS GP if possible, as this will facilitate the process.
Link to UK Government’s statement on AstraZeneca COVID19 vaccine following updated advice from the UK’s medicines regulator (published 7th of April 2021)
https://www.gov.uk/government/news/statement-on-astrazeneca-covid-19-vaccine-following-mhra-update